This project is designed to identify and characterize the protein specified by the transforming gene of Moloney murine sarcoma virus. We intend to use cloned viral DNA, already prepared, to isolate viral specific intracellular RNA for use as template in vitro translation. A variety of non-mouse host animals have been immunized with Moloney sarcoma transformed cells with the hope of obtaining anti-serum reactive to the viral transforming protein. The cellular sequence homologous to the viral transforming gene will be studied by Southern gel filter transfer and molecular cloning.